Display device and method for manufacturing the same

ABSTRACT

An object of the present invention is to provide such a sealing structure that a material to be a deterioration factor such as water or oxygen is prevented from entering from external and sufficient reliability is obtained in a display using an organic or inorganic electroluminescent element. In view of the above object, focusing on permeability of an interlayer insulating film, deterioration of an electroluminescent element is suppressed and sufficient reliability is obtained by preventing water entry from an interlayer insulating film according to the present invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device formed using anelement (light emitting element) which has a light-emitting materialinterposed between electrodes and emits light by applying currentbetween the electrodes, and particularly, to a sealing structure of alight emitting element in such a display device.

2. Description of the Related Art

In recent years, a thin and lightweight display using a light emittingelement has actively been developed. The light emitting element isformed by interposing a material which emits light by applying currentbetween a pair of electrodes. A light source such as back light is notrequired since it itself emits light unlike in the case of liquidcrystal, and the element itself is very thin. Therefore, it is extremelyadvantageous to form a thin and lightweight display.

Although the light emitting material of the light emitting elementincludes an organic one and an inorganic one, a light emitting elementusing an organic material that is driven with low voltage is oftenconsidered the most preferable. Drive voltage of a display having alight emitting element using an organic material is from 5 V to 10 V,and it is understood that it can be driven with very low voltagecompared to an electroluminescent device using an inorganic materialwhich requires drive voltage of from 100 V to 200 V. Drive voltage of aliquid crystal display singing the praises of low power consumption isapproximately from 5 V to 15.5 V, and it is understood that the displayhaving the light emitting element using an organic material can bedriven with equal to or lower voltage than a liquid crystal display.

However, one background of not reaching a practical use yet while havingsuch advantages is a problem of reliability. The light emitting elementusing an organic material often deteriorates due to moisture, and has adefect of being hard to obtain long-term reliability. The light emittingelement which is deteriorated due to moisture causes decrease inluminance or does not emit light. It is conceivable that this causes adark spot (black spot) and a shrink (decrease in luminance from an edgeportion of a display device) in a display device using the lightemitting element.

Various countermeasures are suggested to suppress such deterioration(for example, Reference 1: Japanese Patent Laid-Open No. 9-148066, andReference 2: Japanese Patent Laid-Open No. 13-203076).

However, sufficient reliability is not obtained yet even when thesecountermeasures are taken, and thus, further improvement in reliabilityis expected.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide such a sealingstructure that a material to be a deterioration factor such as water oroxygen is prevented from entering from external and sufficientreliability is obtained in a display using an organic or inorganic lightemitting element.

In view of the above object, deterioration of a light emitting elementis suppressed and sufficient reliability is obtained by preventing waterentry from an interlayer insulating film according to the presentinvention. In the present invention, at least one side of substrates islight transmitting in a light emitting device having a pixel portionmade up of a light emitting element interposed between the substrates.

One structure of the present invention is a light emitting devicecomprising a light emitting element interposed between a pair ofsubstrates, at least one of which is light transmitting, wherein thelight emitting element is formed to be in contact with one of or both afirst interlayer insulating film and a second interlayer insulatingfilm, and a peripheral portion of the first interlayer insulating filmand the second interlayer insulating film comprises: a first openingwhich penetrates the first interlayer insulating film; a firstimpermeable protective film covering the first opening and the firstinterlayer insulating film in the first opening; and a second openingwhich penetrates the second interlayer insulating film.

Another structure of the present invention is a light emitting devicecomprising a light emitting element interposed between a pair ofsubstrates, at least one of which is light transmitting, wherein thelight emitting element is formed to be in contact with one of or both afirst interlayer insulating film and a second interlayer insulatingfilm, and a peripheral portion of the first interlayer insulating filmand the second interlayer insulating film comprises: a first openingwhich penetrates the first interlayer insulating film; a firstimpermeable protective film covering the first opening and the firstinterlayer insulating film in the first opening; a second opening whichpenetrates the second interlayer insulating film; and a secondimpermeable protective film covering the second opening and the secondinterlayer insulating film in the second opening and in contact with thefirst impermeable protective film on a bottom face of the secondopening.

Another structure of the present invention is a light emitting devicecomprising a light emitting element interposed between a pair ofsubstrates, at least one of which is light transmitting, wherein thelight emitting element is formed to be in contact with one of or both afirst interlayer insulating film and a second interlayer insulatingfilm, a peripheral portion of the first interlayer insulating film andthe second interlayer insulating film comprises: a first opening whichpenetrates the first interlayer insulating film; a first impermeableprotective film covering the first opening and the first interlayerinsulating film in the first opening; a second opening which penetratesthe second interlayer insulating film; and a second impermeableprotective film covering the second opening and the second interlayerinsulating film in the second opening and in contact with the firstimpermeable protective film on a bottom face of the second opening, andthe pair of substrates is fixed to each other with an impermeablecomposition in a region provided with the first opening and the secondopening or in an outer side of the region.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the second impermeableprotective film comprises the same material as an anode or cathode ofthe light emitting element.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the light emitting element isprovided with a pixel portion connected to a thin film transistor.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the first impermeableprotective film is made of the same material as a source electrode and adrain electrode of the thin film transistor.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a semiconductor film is formedin a lower portion of the first opening.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a metal film is formed in alower portion of the first opening.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a semiconductor film is formedin a lower portion of the first opening, and the semiconductor film ismade of the same material as an active layer of the thin filmtransistor.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a metal film is formed in alower portion of the first opening, and the metal film is made of thesame material as a gate electrode of the thin film transistor.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein at least a portion of a bottomface of the first opening and a portion of the bottom face of the secondopening are formed in the same position on a face of the substrate.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a bottom face of the firstopening and the bottom face of the second opening are formed in adifferent position on a face of the substrate.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a plurality of the firstopenings and the second openings is formed.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein at least one layer of thefirst interlayer insulating film and the second interlayer insulatingfilm is made of an organic material.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein at least one layer of thefirst interlayer insulating film and the second interlayer insulatingfilm is made of an inorganic material.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein at least one layer of thefirst interlayer insulating film and the second interlayer insulatingfilm is made of a siloxane film.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the organic material isacrylic or polyimide.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the first impermeableprotective film or the second impermeable protective film is a siliconnitride film.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the first impermeableprotective film and the second impermeable protective film are siliconnitride films.

Another structure of the present invention is a light emitting devicecomprising a light emitting element interposed between a pair ofsubstrates, at least one of which is light transmitting, wherein thelight emitting element is formed to be in contact with an interlayerinsulating film, and a side edge portion of the interlayer insulatingfilm formed inside not to reach an edge portion of the substrate isprocessed into a tapered shape.

Another structure of the present invention is a light emitting devicecomprising a light emitting element interposed between a pair ofsubstrates, at least one of which is light transmitting, wherein thelight emitting element is formed to be in contact with an interlayerinsulating film, a side edge portion of the interlayer insulating filmformed inside not to reach an edge portion of the substrate is processedinto a tapered shape, and an impermeable protective film is formed inthe side edge portion of the interlayer insulating film.

Another structure of the present invention is a light emitting devicecomprising a light emitting element interposed between a pair ofsubstrates, at least one of which is light transmitting, wherein thelight emitting element is formed to be in contact with an interlayerinsulating film, a side edge portion of the interlayer insulating filmformed inside not to reach an edge portion of the substrate is processedinto a tapered shape, an impermeable protective film is formed in theside edge portion of the interlayer insulating film, and the pair ofsubstrates is fixed to each other with an impermeable composition in aregion of the side edge portion of the interlayer insulating film or inan outer side of the region.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the light emitting element isprovided with a pixel portion connected to a thin film transistor.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a semiconductor film is formedfrom a bottom portion of the interlayer insulating film to the edgeportion of the substrate.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a metal film is formed from alower portion of the interlayer insulating film to the edge portion ofthe substrate.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a semiconductor film is formedfrom a lower portion of the interlayer insulating film to the edgeportion of the substrate, and the semiconductor film is made of the samematerial as an active layer of the thin film transistor.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein a metal film is formed from alower portion of the interlayer insulating film to the edge portion ofthe substrate, and the metal film is made of the same material as a gateelectrode of the thin film transistor.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the interlayer insulating filmis made of an organic material.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the interlayer insulating filmis made of an inorganic material.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the interlayer insulating filmis made of a siloxane film.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the organic material isacrylic or polyimide.

Another structure of the present invention is a light emitting deviceaccording to the above structure, wherein the impermeable protectivefilm is a silicon nitride film.

Another structure of the present invention is a light emitting devicecomprising: a pixel portion made up of a light emitting elementinterposed between a pair of substrates, at least one of which is lighttransmitting; an external connection portion taking in a signal fromexternal; and a plurality of wirings connecting the pixel portion andthe external connection portion, wherein the pair of substrates is fixedto each other with an impermeable composition between the pixel portionand the external connection portion, the light emitting element isformed to be in contact with an interlayer insulating film, a part ofthe interlayer insulating film is located between adjacent wirings inthe plurality of wirings, and the wiring is thickly provided with aplurality of bends in a lower portion of or inside a portion in whichthe substrates are fixed to each other with the impermeable composition.

According to the above structures, deterioration of a light emittingelement in an electroluminescent device can be suppressed. In addition,reliability can drastically be improved.

These and other objects, features, and advantages of the presentinvention will become more apparent upon reading of the followingdetailed description along with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C show Embodiment Mode 1.

FIGS. 2A and 2B show a conventional structure.

FIG. 3 is a top view of an electroluminescent device.

FIGS. 4A and 4B show variation of Embodiment Mode 1.

FIGS. 5A and 5B show Embodiment Mode 2.

FIGS. 6A to 6C show Embodiment Mode 3.

FIGS. 7A and 7B show Embodiment Mode 3.

FIGS. 8A to 8C show a conventional structure.

FIGS. 9A to 9C show Embodiment Mode 4.

FIGS. 10A to 10F show Embodiment Mode 4.

FIGS. 11A and 11B show Embodiment Mode 5.

FIGS. 12A to 12C show Embodiment Mode 6.

FIGS. 13A to 13D show Embodiment Mode 6.

FIGS. 14A and 14B show Embodiment 1.

FIGS. 15A and 15B show Embodiment 1.

FIGS. 16A and 16B show Embodiment 1.

FIG. 17 shows Embodiment 2.

FIGS. 18A to 18I show Embodiment 2.

FIGS. 19A and 19B show Embodiment 3.

FIG. 20 shows Embodiment 4.

FIGS. 21A to 21J show Embodiment 5.

FIGS. 22A to 22D are SEM pictures and pattern diagrams showingEmbodiment 5.

FIGS. 23A to 23 E show examples of electronic devices.

DETAILED DESCRIPTION OF THE INVENTION

A mode carrying out the present invention is described hereinafter. Notethat the same number refers to the same part or similar part in adrawing. In addition, description on the same part is omitted.

Embodiment Mode 1

In an electroluminescent device, an insulating film such as a siliconoxide film, a silicon nitride film, an acrylic film, a polyimide film,or a siloxane film is often used as an interlayer insulating film.Specifically, an acrylic film or a siloxane film is a preferablematerial since it can be formed by application and it has highplanarity. However, it has comparatively high permeability on the otherhand.

FIGS. 2A and 2B are cross-sectional views taken along a line b-b′ inFIG. 3. In the case of conventional structures as shown in FIGS. 2A and2B, an end face 2 of an interlayer insulating film 1 is always exposedto outer atmosphere. Therefore, there is a case that water entersthrough the interlayer insulating film and deterioration of a lightemitting element is caused, even when an upper portion thereof iscovered with an impermeable sealant 3 so that a light emitting element 4is not exposed to outer air.

Thus, one of structures in the present invention for solving the problemis described with reference to FIGS. 1A to 1C. FIGS. 1A to 1C show anexample of reducing water entry through the interlayer insulating filmby covering inside of a groove formed on the periphery of the interlayerinsulating film with an impermeable film (hereinafter, referred to as aprotective film). FIGS. 1A to 1C correspond to a cross section takenalong a line d-d′ in FIG. 3, for example. Note that a sealant made of animpermeable material and an opposing substrate are omitted in FIGS. 1Aand 1B. A state of the periphery of an electroluminescent device isshown. Reference numeral 100 denotes a substrate; 101, a base insulatingfilm; 102, a first interlayer insulating film; 103, a first protectivefilm; 104, a second interlayer insulating film; and 105, a secondprotective film.

In this structure, the first interlayer insulating film 102 and thesecond interlayer insulating film 104 are assumed comparatively highlypermeable. In these highly permeable films, a groove-shaped opening 106that penetrates each film in a thickness direction is formed. Theprotective films 103 and 105 are formed to cover at least inside of thegroove (to continuously cover an end face of an exposed interlayerinsulating film and a film in a lower portion). In addition, theprotective films 103 and 105 are in contact with each other at theopening 106.

When such a structure is employed, water entered from edge portions ofthe interlayer insulating films 102 and 104 is prevented from furtherentering by the impermeable protective films 103 and 105 formed on anend face of the groove-shaped opening 106. Since the groove-shapedopening 106 is formed to penetrate in a thickness direction, an entrypath of water is blocked without providing the protective film.Therefore, providing the groove-shaped opening alone becomes acountermeasure for deterioration of a light emitting element due towater, depending on desired degree of reliability.

The groove-shaped opening 106 is the most effective when continuouslyformed all around the periphery of the permeable film. However, when itis impossible, a certain degree of effect can be expected by forming theopening only on one side or partially since water entry at least fromthe portion can be reduced.

In FIGS. 1A to 1C, the groove-shaped opening 106 is repeatedly providedfrom the periphery of the interlayer insulating film to a regionprovided with a light emitting element, but only one groove-shapedopening 106 may as well be provided. However, reliability is furtherimproved by repeatedly taking such measures.

When the protective films 103 and 105 are made of a wiring material,they can be used as a lead wiring which can be disposed on an outerboundary. Further, a difference between FIG. 1A and FIG. 1B is adifference whether the protective films 103 and 105 are independent ineach opening or not. When employing such an independent structure ineach opening as shown in FIG. 1B, the protective film in each openingcan be used as a separate wiring.

Other structures of suppressing water entry by such a groove-shapedopening and a protective film are conceivable, and some examples of themare given in FIGS. 4A and 4B. Cross-sectional views shown in FIGS. 4Aand 4B also correspond to a line d-d′ in FIG. 3 or the like. Inaddition, a sealant made of an impermeable material and an opposingsubstrate are omitted.

FIGS. lA to 1C show an example that positions of a first opening formedin the first interlayer insulating film 102 and a second opening formedin the second interlayer insulating film 104 are the same; however,FIGS. 4A and 413 show an example that positions of the first openingformed in the first interlayer insulating film 102 and the secondopening formed in the second interlayer insulating film 104 aredifferent. Even such a structure can achieve an effect similar to thestructure as shown in FIGS. 1A to 1C and can be formed in a short timesince the second opening is shallower than that in FIGS. 1A to 1C. Inaddition, less attention to disconnection between steps needs to be paidsince level difference becomes small, In FIG. 4A and FIG. 413, aposition in which an opening is formed is difference. Reference numeral101′ denotes a base insulating film in FIGS. 4A and 4B.

In addition, the substrate 100 provided with the light emitting elementis fixed to an opposing substrate 108 with a sealant 107 made of animpermeable material, and the light emitting element is sealed from theoutside. The sealant is more effective in suppressing water entry whenformed in an upper portion of the groove-shaped opening 106.

In this embodiment mode, the case of two layers of the interlayerinsulating films is described; however, the present invention can beapplied in the case of one layer.

Embodiment Mode 2

In this embodiment mode, an example of a structure for preventing waterfrom entering by removing a permeable film on the periphery of asubstrate from the periphery of the substrate to a certain distance isdescribed with reference to FIGS. 5A and 5B. Here, the permeable film isassumed an interlayer insulating film. However, an object is not limitedto the interlayer insulating film and the present invention can beapplied as a countermeasure for the permeable film. The cross-sectionalviews correspond to a line e-e′ in FIG. 3.

Reference numeral 120 denotes a portion from which the interlayerinsulating films 102 and 104 are removed on an end face of a substratein FIG. 5A. In Embodiment Mode 1, the end faces of the interlayerinsulating films 102 and 104 are exposed to outer air. Then, appropriatedistance of the interlayer insulating films 102 and 104 on the end faceof the substrate is removed in this embodiment mode, and the end facesthereof are covered with the protective films 103 and 105. Accordingly,exposure of the end face of the permeable film to outer air can beprevented; therefore, water entry itself can be blocked.

When the sealant 107 made of an impermeable material is formed on anouter side of the end face of the interlayer insulating film coveredwith the protective film or is formed to cover the entire end face ofthe interlayer insulating film in fixing the opposing substrate 108,water entry can further be prevented. Therefore, improvement inreliability can be expected. Reference numeral 101′ denotes a baseinsulating film in FIGS. 5A and 5B.

In addition, other structures in this embodiment mode are conceivable,and one example of them is shown in FIG. 5B. A difference between FIG.5B and FIG. 5A is a removed position of the interlayer insulating films102 and 104 at the end face of the substrate. FIG. 5A shows a structurein which the end face of the second interlayer insulating film 104 islocated on the further outer side of the substrate than the end face ofthe first interlayer insulating film 102, and FIG. 5B shows a structurein which the end face of the first interlayer insulating film 102 islocated on the further outer side of the substrate than the end face ofthe second interlayer insulating film 104.

Note that two layers of the interlayer insulating films are used in thisembodiment mode; however, the present invention can be applied to anelectroluminescent device having one layer of an interlayer insulatingfilm.

Moreover, this embodiment mode is more effective when combined withEmbodiment Mode 1.

Embodiment Mode 3

As is obvious referring to FIGS. 6A to 6C, in the case of manufacturinga sealing structure of the present invention, an opening 106 and aninterlayer insulating film removed portion 120 on an end face of asubstrate can be formed simultaneously with opening of a contact holeformed in interlayer insulating films 102 and 104, which is effective.

However, a contact hole is etched under such a condition that theinterlayer insulating film and a gate insulating film can be etchedusing a silicon semiconductor layer as an etching stopper. In theopening 106 and the interlayer insulating film removed portion 120 wherean etching stopper does not exist, an etching residue may be generated,or a base insulating film 101 may be sharpened, thereby generatingunevenness, in etching the first interlayer insulating film 102.

FIG. 7A is a SEM picture of a sample in which a siloxane film is formedover a base film as an interlayer insulating film, a silicon nitridefilm is formed thereover, a part of the interlayer insulating film isremoved under an opening condition of a contact hole, and then a wiringis provided. Regions indicated by “C” and “c” are regions from which theinterlayer insulating film is removed, and regions “a”, “b”, and “c” areprovided with a wiring. A region “A” is an original surface withoutbeing etched, “B” is an end face of the interlayer insulating film, and“C” is a surface of the base insulating film.

As is obvious seeing this, small unevenness as shown in the region “C”is generated when a contact hole is formed in the interlayer insulatingfilm under the contact hole opening condition to reach the baseinsulating film. Then, large unevenness as shown in the region “c” isgenerated by forming a wiring thereover. It is obvious from evenness ofa wiring formed over the region “a” that this unevenness is caused byunevenness over the base insulating film after forming the opening. Thewiring can be used as a protective film, and this may cause to generateunevenness over the protective film. In addition, coverage of the wiringitself becomes poor.

When such large unevenness is generated, adhesiveness of a sealant madeof an impermeable material to be formed thereover may be in danger ofbeing significantly affected. This is because water enters from aportion having poor adhesiveness when the sealant has poor adhesiveness,even when the sealant itself has low permeability.

As in FIG. 7A, FIG. 7B is a SEM picture of a sample in which a siloxanefilm is formed over a base insulating film as an interlayer insulatingfilm, the interlayer insulating film is removed under the contact holeopening condition, and then a wiring is provided. The region “C” in FIG.7A corresponds to a region “D” in FIG. 7B, and the region “D” is asurface from which the interlayer insulating film is removed under thecontact hole opening condition after forming a base insulating film andan interlayer insulating film in this order over the substrate. Theregion “c” in FIG. 7A corresponds to a region “E” in FIG. 7B, and theregion “E” is a surface in which a wiring is formed over the region “D”in FIG. 7B.

On the other hand, a region “F” in FIG. 7B is a surface of a portionfrom which the interlayer insulating film is removed under the contacthole opening condition similarly as in the region “D” in FIG. 7B afterforming the base insulating film, a silicon film, and the interlayerinsulating film in this order over the substrate, that is, forming thesilicon film serving as an etching stopper over the base insulating filmand forming the interlayer insulating film thereover. Briefly, it has astructure of the region “D” in FIG. 7B provided with an etching stopperof the silicon film. Since the silicon film in the region “F” is removedby etching in forming the wiring in “E”, the base insulating film can beseen similarly as in the region “D” in FIG. 7B. The region “F” has avery even surface in comparison with “D” in which a silicon film is notformed under the interlayer insulating film.

This is because the silicon film serves as an etching stopper film andsuppresses generation of an etching residue of the interlayer insulatingfilm in etching the interlayer insulating film and generation ofunevenness due to gouge of the base insulating film.

On the basis of this, in this embodiment mode, etching stopper films 130and 131 are formed in advance in a position to be provided with theopening 106 in FIGS. 1A to 1C and the interlayer insulating film removedportion 120 in FIGS. 5A and 5B (FIG. 6A). Cross-sectional views shown inFIGS. 6A to 6C correspond to a cross-section taken along a line f-f′ inFIG. 3.

An example of forming such etching stopper films 130 and 131 by using asilicon film forming a semiconductor layer 132 of a thin film transistor(TFT) manufactured in a driver circuit portion or a pixel portion isdescribed in this embodiment mode. However, any film can be used as theetching stopper films 130 and 131 as long as it functions as an etchingstopper of the opening 106 and the interlayer insulating film removedportion 120 in removing the interlayer insulating film. It may be madeof the same material as the semiconductor layer 132 simultaneously withformation of the semiconductor layer 132 as in this embodiment mode; itmay be made of the same material as the gate electrode 133simultaneously with formation of the gate electrode; or it mayseparately be made of another material. When it is formed simultaneouslywith the semiconductor layer 132 or the gate insulating film, it isadvantageous since the number of processes does not increase.

The opening 106 and the interlayer insulating film removed portion 120are formed simultaneously with a contact hole opening for the wiring. Inthis case, the etching stopper films 130 and 131 (silicon film) areformed in a lower portion of the opening 106 and the interlayerinsulating film removed portion 120 in a light emitting device of thepresent invention. Therefore, unevenness due to an etching residue orgouge of the interlayer insulating film is not generated. If a wiring134 to be formed later is formed to cover inside of the opening 106 andthe end face of the interlayer insulating film in the interlayerinsulating film removed portion 120, it also functions as a protectivefilm 103. When the interlayer insulating film is removed using theetching stopper films 130 and 131, an etching residue or gouge over alower film is not generated. Consequently, adhesiveness of theprotective film 103 can be prevented from decreasing, and generation ofunevenness on the protective film can be suppressed.

In this embodiment mode, the protective film 103 is made of the samemetal film as a material for the wiring 134, and can be formedsimultaneously with the step of forming the wiring. However, it may bemade of another material in a different step.

In addition, the protective film 103 may further be covered with amaterial for an anode 135 of the light emitting element over a switchingTFT of a pixel portion to be formed later. It can be expected that waterentry can further be suppressed (FIG. 6B).

An opposing substrate 108 is fixed with a sealant 107 made of animpermeable material after forming the light emitting element. Thesealant can block an entry path of water by being applied over thegroove-shaped opening 106 and/or the interlayer insulating film removedportion 120 on the periphery of the substrate. Therefore, the sealant ishighly effective in suppressing deterioration of the light emittingelement. The light emitting element is formed by interposing a lightemitting layer 137 between the anode 135 and a cathode 138, and thelight emitting element is separated from every element by a partition136 (FIG. 6C).

When this embodiment mode is applied, generation of unevenness of theprotective film 103 over the groove-shaped opening 106 and theinterlayer insulating film removed portion 120 on the periphery of thesubstrate are suppressed. Therefore, deterioration of adhesiveness ofthe sealant can be prevented, and water entry from a portion having pooradhesiveness can be suppressed, which improves reliability.

This embodiment mode can freely be combined with Embodiment Mode 1 or 2.When combined, water entry from external can further be prevented;accordingly, reliability of an electroluminescent device can further beimproved.

Embodiment Mode 4

In this embodiment mode, a structure is described, which can suppress aneffect of water entered through an interlayer insulating film in astructure in which it is difficult to remove an entire interlayerinsulating film.

As described in Embodiment Modes 2 and 3, it is a very effective meansof preventing water entry to remove an interlayer insulating film on theperiphery of a substrate and not to expose an end face of an interlayerinsulating film to outer air as much as possible by covering the endface of the interlayer insulating film with a protective film 103 (and105) and a sealant 107. However, there may be a case that it isdifficult to remove an entire interlayer insulating film, depending on astructure.

For example, a wiring portion connecting an external terminal and aninternal circuit is considered (a region “c” in FIG. 3). The wiring isformed by removing an interlayer insulating film on the periphery of asubstrate, forming a metal film serving as a wiring, and etching themetal film to have a desired shape of a wiring, when a structure inwhich an interlayer insulating film on the periphery of a substrate isremoved (a structure in which an interlayer insulating film removedportion 120 is formed: Embodiment Modes 2 and 3) is employed.

However, there is a step 12 that an end face of an interlayer insulatingfilm forms between a portion 10 from which an interlayer insulating film15 is removed and a portion 11 in which the interlayer insulating filmremains. There is a case that a metal film formed in this portion is notsufficiently etched and remains. Such an etching residue 13 makesadjacent wirings 14 short circuit and causes a defect.

A measure that an interlayer insulating film 16 is left between thewirings 14 is taken as shown in FIG. 9 to lessen the interlayerinsulating film which is exposed to outer air while preventing the shortcircuit. Accordingly, a defect due to the above described short circuitcan be prevented with most of the interlayer insulating film preventedfrom being exposed to outer air. However, the interlayer insulating filmleft between the wirings cannot be removed and is always exposed toouter air; therefore, water entry from the portion cannot be prevented.Water entry from the interlayer insulating film remaining between thewirings may have an adverse effect when considered from the point ofview of long-term reliability.

Water entry through the interlayer insulating film is caused by adiffusion phenomenon of water in the film. As for the diffusionphenomenon, it is assumed that time to reach a certain position isproportional to square of distance as is found by a formula ofdiffusion. Namely, when only the interlayer insulating film left betweenthe wirings is an entry path of water, time for water which enters bydiffusing in the interlayer insulating film left between electrodes toreach inside of an electroluminescent device can effectively belengthened by taking the distance as long as possible.

Conventionally, the wiring portion which connects an external terminaland an internal circuit is straight as shown in FIG. 10A besides a placewhere a bend is necessary in terms of layout, such as a corner. Thewiring 14 is thickly provided with a plurality of bends as shown in FIG.10B.

Then, substantial length of the interlayer insulating film 16 existingbetween the wirings can be lengthened, and a distance for water todiffuse in the interlayer insulating film before reaching inside of theelectroluminescent device becomes longer. Consequently, time to start todeteriorate can largely be obtained, and longer-term reliability can besecured than ever before.

FIGS. 10C to 10F show examples of other conceivable structures forrealizing this embodiment mode. When length of the interlayer insulatingfilm between wirings gets longer even a little than the conventionalstructure in FIG. 10A, water entry can further be delayed than everbefore. A desired pattern may be formed depending on necessity.

When this embodiment mode is applied, area of the interlayer insulatingfilm between the wirings when looked from above of a light emittingdevice becomes large. Therefore, it is important to dispose a bend ofthe wiring in such a position that it is not exposed to outer air, thatis, inside a sealant made of an impermeable material or in a lowerportion of the sealant.

This embodiment mode can be applied by appropriately combining withEmbodiment Modes 1 to 3. It is possible to effectively prevent waterentry by separately applying Embodiment Modes according to its location,for example, applying this embodiment mode to a wiring portionconnecting an external terminal and an internal circuit of anelectroluminescent device (a region “c” in FIG. 3 or the like), andEmbodiment Modes 1 and 2 to other outer peripheral portions. Further, inthis embodiment mode, there is a step of removing an interlayerinsulating film in forming a wiring portion. When the structure inEmbodiment Mode 3 is employed on that occasion, generation of unevennessover the wiring can be suppressed. Therefore, adhesiveness of a sealantmade of an impermeable material is improved, and water entry from aninterface between the sealant and the wiring can drastically bedecreased.

Embodiment Mode 5

In this embodiment mode, a mode which can remove an interlayerinsulating film on the periphery of a substrate also in a wiring portion(a region “c” in FIG. 3 or the like) connecting an external terminal andan internal circuit and prevent water entry through an interlayerinsulating film is described with reference to FIGS. 11A and 11B.

It is only in a step 12 on an end face of an interlayer insulating film15 where an etching residue is generated since it cannot be etched, asshown in FIG. 8. Since the end face of the interlayer insulating film issteep, a wiring material may not be etched by anisotropic dry etchingemployed for wiring formation and may remain in this portion. In such awiring portion, it is difficult to employ isotropic etching typified bywet etching in terms of a margin of the wiring.

Thus, the end face 17 of the interlayer insulating film 18 is processedinto a gently tapered shape in this embodiment mode. Accordingly, awiring can certainly be etched even on the end face 17 of the interlayerinsulating film, and an etching residue can be prevented fromgenerating; therefore, it becomes unnecessary to leave the interlayerinsulating film between the wirings 14 (FIGS. 11A and 11B).

As a result, the interlayer insulating film on the periphery of asubstrate can entirely be removed in the wiring portion (a region “c” inFIG. 3 or the like) connecting an external terminal and an internalcircuit. Moreover, a water path through the interlayer insulating filmcan completely be blocked by covering whole outer periphery than aposition where the interlayer insulating film exists with an impermeablesealant. Then, reliability of an electroluminescent device candrastically be improved.

Note that the tapered end face of the interlayer insulating film may beprocessed with an inert gas such as argon. This densifies an end face ofthe wiring, and has an effect of making it harder for an impurity suchas water to enter, compared to the case without processing. In addition,it is preferable to further form a nitride film such as a siliconnitride film to cover the tapered end face of the interlayer insulatingfilm, since water entry from the end face can similarly be suppressed.

This embodiment mode can be applied by appropriately combining withEmbodiment Modes 1 and 2. It is possible to effectively prevent waterentry by separately applying Embodiment Modes according to its locationand necessity, for example, applying this embodiment mode to a wiringportion connecting an external terminal and an internal circuit of anelectroluminescent device, and Embodiment modes 1 and 2 to another outerperipheral portion.

Embodiment Mode 6

An example of combining Embodiment Mode 5 and Embodiment Mode 3 isdescribed in this embodiment mode.

In this embodiment mode combining Embodiment Mode 5 and Embodiment Mode3, an etching stopper film 20 is formed in a portion 10 from which aninterlayer insulating film is removed in order to suppress generation ofunevenness caused in etching an interlayer insulating film. In thiscase, a film serving as an etching stopper is formed in a lower portionof a remaining interlayer insulating film 15 in terms of a margin 21 forforming an end face of an interlayer insulating film into a taperedshape (FIG. 12A).

The etching stopper film 20 is formed over an entire surface of theinterlayer insulating film removed portion 10, and a wiring 14 is formedthereover. Therefore, when the etching stopper film 20 has conductivity,all the wirings formed in the interlayer insulating film removed portionare short-circuited. However, the etching stopper film in a position 22where a wiring is not formed is etched and removed with an unnecessarymetal film in etching for forming a wiring shape, or is removed byperforming appropriate etching again in the case where it cannot beremoved by wiring etching. Therefore, there is no need to worry about ashort circuit between wirings in the portion. However, an etchingstopper film 23 located in a lower portion of the above describedremaining interlayer insulating film (the etching stopper film 20 in aposition of a taper formation margin 21) remains without being removedsince it is covered with the interlayer insulating film. When the filmhas conductivity, a problem that wirings are short-circuited through theportion is caused (ref. FIG. 12B).

Such a problem does not occur when the etching stopper film is made ofan is insulating film. However, in the case of forming the etchingstopper film without increasing the number of steps, the problem notablyoccurs since a conceivable film is a silicon film used for asemiconductor layer or a metal film used for a gate electrode and bothof them have conductivity.

In this embodiment mode, among the etching stopper film formed below theinterlayer insulating film, an etching stopper film is not formedbetween wirings from the beginning (FIGS. 13A to 13D). Among the etchingstopper film formed below the interlayer insulating film, an etchingstopper film is formed to be separated from the etching stopper filmlocated in a lower portion of the wiring (FIGS. 18F to 18I).

When this structure is employed, generation of unevenness in removing aninterlayer insulating film can be suppressed also in a wiring portionconnecting an external terminal and an internal circuit and unevennessof a wiring can also be suppressed. Accordingly, decrease inadhesiveness of a sealant due to unevenness of a lower film can beprevented, and water entry from a portion having poor adhesiveness of asealant can drastically be reduced. Consequently, reliability of anelectroluminescent device is exceedingly improved.

Embodiment 1

In this embodiment, a detailed embodiment of Embodiment Mode 1 andEmbodiment Mode 2 is described with reference to FIGS. 14A and 14B, 15Aand 15B, and 16A and 16B.

A first interlayer insulating film 225 is formed over a substrate 200provided with a base insulating film 201, a driver circuit transistor(only an n-channel thin film transistor 203 and a p-channel thin filmtransistor 204 are shown in the drawing), and a thin film transistor ina pixel portion (only a switching transistor 205 and a current controltransistor 206 are shown in the drawing).

An insulating substrate such as a glass substrate, a quartz substrate,or a crystalline glass, a ceramic substrate, a stainless steelsubstrate, a metal substrate (tantalum, tungsten, molybdenum, or thelike), a semiconductor substrate, a plastic substrate (polyimide,acrylic, polyethylene terephthalate, polycarbonate, polyarylate,polyethersulfone, or the like), or the like can be used as the substrate200, but a material which can withstand at least heat generated during aprocess. In this embodiment, a glass substrate is employed.

A silicon oxide film, a silicon nitride film, a silicon oxynitride film,or the like can be used as the base insulating film 201. These areformed by using a known method such as sputtering, low pressure CVD,plasma CVD, or the like. In this embodiment, a silicon nitride oxidefilm is formed to be 100 nm in thickness.

Subsequently, an amorphous semiconductor film is formed. The amorphoussemiconductor film may be made of silicon or a material containingsilicon as its main component (for example, SixGe1−x, or the like) tohave a desired thickness. As a manufacturing method, a known method suchas sputtering, low pressure CVD, plasma CVD can be employed. In thisembodiment, the amorphous semiconductor film is made of amorphoussilicon to be 50 nm in thickness.

Next, amorphous silicon is crystallized. A step of performing lasercrystallization after adding an element that promotes crystallizationand crystallizing by heat treatment is described in this embodiment.

A thin film of a nickel solution is formed on the surface of thesemiconductor film by applying with a spinner a nickel acetate solutionor a nickel nitrate solution containing nickel in a concentration offrom 5 ppm to 10 ppm in terms of weight. The nickel element may besprayed on the whole surface of the semiconductor film by sputteringinstead of application. As a catalytic element, one of or a plurality ofelements such as iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt(Co), platinum (Pt), copper (Cu), and gold (Au) may be used as well asnickel (Ni).

Subsequently, the amorphous semiconductor film is crystallized by heattreatment. It may be carried out at a temperature of from 500° C. to650° C. for about 4 hours to 24 hours since a catalytic element is used.The semiconductor film becomes a crystalline semiconductor filmaccording to this crystallization process.

Subsequently, crystallization by a laser is performed to improvecrystallinity. For laser crystallization, a pulse oscillation orcontinuous oscillation gas, solid, or metal laser oscillation device maybe used. A laser oscillated from a laser oscillation device may beradiated in a linear shape by using an optical system.

The semiconductor film crystallized by using metal that promotes thecrystallization as in this embodiment contains a metal element used forcrystallization in the film. As this residue may cause variousdisadvantages, the concentration thereof is required to be lowered bygettering.

First, the surface of the crystallized semiconductor film is treatedwith ozone water, and then a barrier film is formed to have a thicknessof from 1 nm to 5 nm, over which a gettering site is formed bysputtering. The gettering site is formed by depositing an amorphoussilicon film containing an argon element of 50 nm in thickness.Thereafter, gettering is carried out by heating at 750° C. for 3 minutesby using a lamp annealing device to remove the gettering site.

After gettering, the crystalline semiconductor film is etched intosemiconductor layers 207 to 210 having desired shapes. Thereafter, agate insulating film 211 is formed. An insulating film containingsilicon may be formed in a thickness of approximately 115 nm by lowpressure CVD, plasma CVD, sputtering, or the like. A silicon oxide filmis formed in this embodiment.

A tantalum nitride (TaN) film of 30 nm in thickness is formed as a firstconductive layer over the gate insulating film 211, and a tungsten (W)film of 370 nm in thickness is formed as a second conductive layerthereover. Note that the first conductive layer is a TaN film of 30 nmin thickness and the second conductive layer is a W film of 370 nm inthickness in this embodiment; however, the present invention is notlimited thereto. The first and second conductive layers may be made ofany element selected from Ta, W, Ti, Mo, Al, Cu, Cr, and Nd, or an alloyor compound material having the above element as a main component.Furthermore, a semiconductor film typified by a polycrystalline siliconfilm doped with an impurity element such as phosphorous may be used. Thefirst conductive layer may be formed to have a thickness of from 20 nmto 100 nm, and the second conductive layer may be formed to have athickness of from 100 nm to 400 nm. In this embodiment, a laminatedstructure of two layers is employed; however, a single layer structuremay be employed, or three or more layers may be laminated as well.

In order to form an electrode and a wiring by etching the conductivelayer, a resist is formed as a mask through exposure to light byphotolithography. First etching treatment is carried out under first andsecond etching conditions. Etching is carried out using the mask made ofa resist to form a gate electrode and a wiring. An etching condition maybe determined in each case.

In this method, ICP (Inductively Coupled Plasma) etching is used. As thefirst etching condition, CF₄, Cl₂, and O₂ are used as an etching gaswith the gas-flow ratio of 25/25/10 (sccm), and a pressure of 1.0 Pa andan RF (13.56 MHz) power of 500 W is applied on a coil electrode togenerate plasma for etching. An RF (13.56 MHz) power of 150 W is appliedto a substrate side (sample stage) to apply a substantially negativeself bias voltage. The W film is etched under the first etchingcondition to make an edge portion of the first conductive layer into atapered shape. An etching rate on the W film under the first etchingcondition is 200.39 nm/min, the etching rate on the TaN film is 80.32nm/min, and the selectivity ratio of W relative to TaN is approximately2.5. Further, a taper angle of the W film is about 26° under the firstetching condition.

Subsequently, etching is carried out under the second etching condition.Etching is performed for about 15 seconds with the resist as a maskremained, by using CF₄ and Cl₂ as an etching gas with the gas-flow ratioof 30/30 (sccm), and a pressure of 1.0 Pa and an RF (13.56 MHz) power of500 W is applied on the coil electrode to generate plasma for etching.An RF (13.56 MHz) power of 20 W is applied to a substrate side (samplestage) to apply a substantially negative self bias voltage. Under thesecond etching condition in which CF₄ and Cl₂ are mixed, both of the Wfilm and the TaN film are etched to the same extent. The edge portionsof the first and second conductive layers become tapered in the firstetching due to bias voltage applied to the substrate.

The second etching is carried out without removing the resist as a mask.The second etching is performed using SF₆, Cl₂, and O₂ as an etching gaswith the gas-flow ratio of 24/12/24 (sccm), and a pressure of 1.3 Pa andan RF (13.56 MHz) power of 700 W is applied on the coil electrode togenerate plasma for etching for about 25 seconds. An RF (13.56 MHz)power of 10 W is applied to a substrate side (sample stage) to apply asubstantially negative self bias voltage. The W film is selectivelyetched under this etching condition to form a conductive layer in asecond shape. The first conductive layer is hardly etched at this time.Gate electrodes including the first conductive layers 212 a to 215 a andthe second conductive layers 212 b to 215 b are formed by the first andsecond etching.

First doping is carried out without removing the resist as a mask. Thus,an N-type impurity is doped in a low concentration into a crystallinesemiconductor layer. The first doping may be performed by ion doping orion implantation. The ion doping may be performed with the dose amountof from 1×10¹³ atoms/cm² to 5×10¹⁴ atoms/cm², and an accelerationvoltage of from 40 kV to 80 kV. The ion doping is carried out at anacceleration voltage of 50 kV in this embodiment. The N-type impuritymay be an element belonging to the group 15 of the periodic tabletypified by phosphorous (P) or arsenic (As). Phosphorous (P) is used inthis embodiment. The first conductive layer is used as a mask to form afirst impurity region (N⁻⁻ region) in a self-aligned manner to which animpurity of low concentration is doped.

Subsequently, the resist as a mask is removed. Then, a mask made of aresist is newly formed and the second doping is carried out at a higheracceleration voltage than the first doping. The N-type impurity is dopedin the second doping as well. The ion doping may be performed with thedose amount of from 1×10¹³ atoms/cm² to 3×10¹⁵ atoms/cm², and anacceleration voltage of from 60 kV to 120 kV. The ion doping is carriedout with the dose amount of 3.0×10¹⁵ atoms/cm² and an accelerationvoltage of 65 kV in this embodiment. The second doping is carried out sothat the impurity element is doped into the semiconductor layer underthe first conductive layer by using the second conductive layer as amask against the impurity element.

By the second doping, a second impurity region (N⁻ region, Lov region)is formed on the part where the second conductive layer is notoverlapped or the part which is not covered with the mask in the partwhere the crystalline semiconductor layer is overlapped with the firstconductive layer. The N-type impurity of which concentration rangingfrom 1×10¹⁸ atoms/cm³ to 5×10¹⁹ atoms/cm³ is doped into the secondimpurity region. Further, the exposed part (third impurity region: N⁺region) which is not covered with either the conductive layer in a firstshape nor the mask is doped with a high concentration N-type impurityranging from 1×10¹⁹ atoms/cm³ to 5×10²¹ atoms/cm³. The semiconductorlayer has an N⁺ region, a part of which is covered only with the mask.The concentration of the N-type impurity of this part is not changedfrom the impurity concentration of the first doping. Therefore, thispart is referred to as the first impurity region (N⁻⁻ region) as it is.

Note that each impurity region is formed by two doping treatment in thisembodiment; however, the invention is not exclusively limited to this.The impurity region having a desired impurity concentration may beformed by one or multiple doping by determining the condition in eachcase.

Subsequently, the resist as a mask is removed and a mask made of aresist is newly formed for third doping. By the third doping, a fourthimpurity region (P⁺ region) and a fifth impurity region (P⁻ region) areformed in which an impurity element having the opposite conductivity tothe ones of the first and second conductive layers is added to asemiconductor layer serving as a P channel TFT.

The fourth impurity region (P⁺ region) is formed on the part which isnot covered with the resist as a mask and not overlapped with the firstconductive layer, and the fifth impurity region (P⁻ region) is formed onthe part which is not covered with the resist as a mask, overlapped withthe first conductive layer, and not overlapped with the secondconductive layer. The P-type impurity element may be boron (B), aluminum(Al), or gallium (Ga), each of which belongs to the group 13 of theperiodic table.

In this embodiment, boron is used as a P-type impurity element to formthe fourth and fifth impurity regions by ion doping using diborane(B₂H₆). Ion doping is carried out with the dose amount of 1×10¹⁶atoms/cm² and an acceleration voltage of 80 kV.

Note that semiconductor layers 207 and 209 for forming N-channel TFTsare covered with the mask made of a resist in the third doping.

The fourth impurity region (P⁺ region) and the fifth impurity region (P⁻region) are doped with phosphorous of different concentrations by thefirst and second doping. However, in both of the fourth impurity region(P⁺ region) and the fifth impurity region (P⁻ region), the third dopingis performed so that the concentration of the P-type impurity element isfrom 1×10¹⁹ atoms/cm² to 5×10²¹ atoms/cm². Therefore, the fourthimpurity region (P⁺ region) and the fifth impurity region (P⁻ region)work as a source region and a drain region of a P-channel TFT withoutproblems.

It should be noted that the fourth impurity region (P⁺ region) and thefifth impurity region (P⁻ region) are formed by once third doping;however, the invention is not exclusively limited to this. The fourthimpurity region (P⁺ region) and the fifth impurity region (P⁻ region)may be formed by multiple doping treatments according to each condition.

By the aforementioned doping treatment, a first impurity region (N⁻⁻region) 216, a second impurity region (N⁻ region, Lov region) 217, thirdimpurity regions (N⁺ region) 218 and 219, fourth impurity regions (P⁺region) 220 and 221, and fifth impurity regions (P⁻ region) 222 and 223are formed.

Thereafter, a first passivation film 224 is formed over a gate electrodeand a gate insulating film. A silicon nitride film, a silicon oxynitridefilm, or a silicon nitride oxide film containing hydrogen is formed asthe first passivation film.

Subsequently, the first interlayer insulating film 225 is formed. Aftera siloxane polymer is entirely applied as the first interlayerinsulating film, it is dried by heat treatment at a temperature of from50° C. to 200° C. for 10 minutes, and baking treatment is performed at atemperature of from 300° C. to 450° C. for 1 hour to 12 hours. Asiloxane film having a thickness of 1 μm, in which a skeletal structureis made up of a bond of silicon (Si) and oxygen (O), is formed over anentire surface by the baking. This step can hydrogenate a semiconductorlayer by hydrogen contained in the first passivation film 224 as well asbaking the siloxane polymer; consequently, the number of steps can bereduced and processes can be simplified.

An inorganic insulating film, an organic material resin, a low-kmaterial, or the like formed by a known method such as a CVD method canbe used for the first interlayer insulating film.

Thereafter, a silicon nitride oxide film or a silicon oxynitride filmmay be formed by a CVD method to cover the first interlayer insulatingfilm 225. When a conductive film to be formed later is etched, this filmfunctions as an etching stopper and can prevent the interlayerinsulating film from being overetched. Further, a silicon nitride filmmay be formed thereover by sputtering. The silicon nitride film has afunction of suppressing movement of an alkaline metal ion; therefore, ametal ion from a pixel electrode to be formed later, such as a lithiumelement or sodium can be prevented from moving to a semiconductor thinfilm.

Subsequently, the first interlayer insulating film is patterned andetched to form a contact hole 226 reaching the thin film transistors 203to 206, a groove-shaped opening 227, and an interlayer insulating filmremoved portion 228 on the periphery of a substrate.

The contact hole 226, the opening 227, and the interlayer insulatingfilm removed portion 228 can be formed by etching the siloxane filmusing a mixed gas of CF₄, O₂, and He, and then etching and removing thesilicon oxide film that is a gate insulating film using a CHF₃ gas.

Subsequently, a metal film is laminated within the contact hole 226 andis patterned to form a source electrode and a drain electrode. In thisembodiment, a titanium film including a nitrogen atom, atitanium-aluminum alloy film, and a titanium film are laminated to be100 nm/350 nm/100 nm in thickness, respectively. Then, the lo films arepatterned and etched into a desired shape to form source/drainelectrodes 229 to 235 and a pixel electrode 236 of three layers.

A titanium film including a nitrogen atom in the first layer is formedby sputtering using titanium as a target with a flow rate of nitrogenand argon set 1:1. When the titanium film including a nitrogen atom asdescribed above is formed over an interlayer insulating film made of asiloxane film, a wiring which is hardly peeled and which has a lowresistance connection with a semiconductor region can be formed.

In this embodiment, a top gate polysilicon TFT is formed in both adriver circuit portion and a pixel portion; however, a TFT in the pixelportion may be a TFT using amorphous silicon as an active layer or a TFTusing microcrystalline silicon as an active layer. In addition, a bottomgate TFT can naturally be used.

At the same time that a source electrode and a drain electrode areformed, a first protective film 237 is made of the same material tocover inside of the groove-shaped opening 227 and an end face of theinterlayer insulating film removed portion 228 on the periphery of thesubstrate.

Subsequently, a second interlayer insulating film 238 is formed over anentire 30 surface of the substrate. The second interlayer insulatingfilm 238 can be made of the same material as the first interlayerinsulating film 225. In this embodiment, the second interlayerinsulating film 238 is made of the same siloxane film as the firstinterlayer insulating film.

Thereafter, a contact hole 239, a groove-shaped opening 240, and aninterlayer insulating film removed portion 241 on the periphery of thesubstrate, which are to be connected to a pixel electrode, are formedunder the same condition as that in etching the first interlayerinsulating film.

In this embodiment, both the first interlayer insulating film 225 andthe second interlayer insulating film 238 are made of a siloxane film;however, a structure of the interlayer insulating film is not limitedthereto. The structure can appropriately be changed to a combination ofan organic film for the first interlayer insulating film and aninorganic film for the second interlayer insulating film, the oppositecombination thereof, a combination of an organic film and an organicfilm, a combination of an inorganic film and an inorganic film, or thelike. A protective film may be formed only over either the firstinterlayer insulating film or the second interlayer insulating filmdepending on permeability of a selected interlayer film.

After a contact hole is formed in the second interlayer insulating film238, a first electrode serving as an anode of a light emitting elementis continuously formed in the contact hole 239 connected to the pixelelectrode and over the second interlayer insulating film 238. Anelectrode of the light emitting element is a laminate of Al—Si(260a)/TiN(260 b)/ITSO(260 c). Here, Al—Si is aluminum containing silicon ofapproximately from 1 atomic % to 5 atomic %, and ITSO is a material inwhich ITO is mixed with SiO₂.

At the same time that the anode of the light emitting element is formed,inside of the groove-shaped opening 240 and the end face of theinterlayer insulating film 238 at the interlayer insulating film removedportion 241 on the periphery of the substrate is covered with aprotective film 242. The protective film may be formed with theelectrodes 260 a to 260 c of the light emitting element. All of thethree layers 260 a to 260 c may be used, or one or two of the layers maybe used.

Subsequently, an insulator 243 is formed to cover an end face of thefirst electrode. The insulator 243 can be made of an inorganic ororganic material. Silicon oxide, silicon oxynitride, siloxane, acrylic,polyimide, or the like can be given. It is preferable to form theinsulator 243 by using a photosensitive organic material, since a shapeof the opening becomes such a shape that a radius of curvaturecontinuously changes and disconnection between the steps or the likehardly occurs when evaporating a light emitting layer.

Then, evaporation is performed with an evaporation source moving byusing an evaporation apparatus. For example, evaporation is performed ina film formation chamber which is vacuum evacuated to 5×10⁻³ Torr (0.665Pa) or less, preferably to from 10⁻⁴ Torr to 10⁻⁶ Torr. When evaporationis performed, an organic compound is previously vaporized by resistanceheating and flies in a direction of the substrate when a shutter isopened in evaporation. The vaporized organic compound flies upwardly andis evaporated to the substrate through an opening provided for a metalmask to form a light emitting layer 244 (including a hole transportlayer, a hole injection layer, an electron transport layer, and anelectron injection layer).

In this embodiment, the light emitting layer is formed by evaporation;therefore, a low molecular weight light-emitting material is used.However, the light emitting layer is formed also by using a highmolecular weight material and an intermediate molecular weight materialhaving characteristics between a low molecular weight material and ahigh molecular weight material. A high molecular weight material can beapplied using spin coating or ink jetting by dissolving into a solvent.In addition, a composite material with an inorganic material as well asan organic material can also be used.

It is assumed that a light emitting mechanism of a light emittingelement emits light in such a way that an electron injected from acathode and a hole injected from an anode form a molecular exciton byrecombining at the center of light emission in an organic compound layerwhen voltage is applied to the organic compound layer interposed betweena pair of electrodes, and energy for light emission is released when themolecular exciton turns back to the ground state. The excited state isknown to include a singlet excited state and a triplet excited state,through either of which light can be emitted.

A light emitting layer typically has a laminated structure. The typicallaminated structure is constituted as “a hole transport layer, anelectroluminescent layer, and an electron transport layer.” Thisstructure has such a high luminous efficiency that light emittingdevices that are recently researched and developed mostly employ thisstructure. A structure in which a hole injection layer, a hole transportlayer, an electroluminescent layer, and an electron transport layer arelaminated over the anode in this order, or a structure in which a holeinjection layer, a hole transport layer, an electroluminescent layer, anelectron transport layer, and an electron injection layer are laminatedover the anode in this order may be employed as well. A fluorescentpigment or the like may be doped into the electroluminescent layer.

Subsequently, a second electrode 245 is formed as a cathode over thelight emitting layer. The second electrode 245 may be made of a thinfilm containing a metal with a low work function (Li, Mg, or Cs). Inaddition, it is preferable that the second electrode is made of alaminated film in which a transparent conductive film (ITO (indium tinoxide), indium zinc oxide (In₂O₃—ZnO), zinc oxide (ZnO), or the like) islaminated over the thin film containing Li, Mg, Cs, or the like.Further, the second electrode may be formed to be from 0.01 μm to 1 μmin thickness by electron beam evaporation, although the film thicknessmay be determined appropriately to serve as a cathode.

Such a light emitting element enables both monochrome display andmulticolor display by selection and arrangement of the light emittinglayer. For monochrome display, all light emitting elements aremanufactured by using one material; however, there are several methodsfor multicolor display. One is a separately coloring method. Theseparately coloring method realize multicolor display by separatelycoloring a light emitting layer which emits light of an objective colorin a necessary portion. Another method is a color conversion method.Light emitting layers are made of one material, and a color conversionlayer is provided only in a necessary portion. Light emitted from thelight emitting layer is converted into a desired color through the colorconversion layer, thereby realizing multicolor display. Another methodis a method for providing a color filter for a white light emittingelement. This method realizes multicolor display by forming a lightemitting layer which emits white light all over the pixel portion and bypassing through a color filter. In all of the methods, the lightemitting layer is formed so that three primary colors of light of RGBare provided every pixel in the case of full color display. Thus, thelight emitting device can perform monochrome, multicolor, and full colordisplay.

An opposing substrate 248 is fixed to the substrate with a sealant 247made of an impermeable material for sealing after a light emittingelement 246 is completed in this way. The sealant 247 made of animpermeable material further firmly blocks off a water entrance andentry path when formed to cover an end face of an interlayer insulatingfilm covered with a protective film in the groove-shaped openings 227and 240 around an insulating film provided with a protective film and inthe interlayer insulating film removed portions 228 and 241 on theperiphery of the substrate, which greatly contributes to improvement inreliability. An impermeable ultraviolet curable resin may be used as thesealant 247 made of an impermeable material.

According to the above described steps, an electroluminescent deviceresistant to deterioration due to water entered from exterior can bemanufactured, and reliability of the electroluminescent device candrastically be improved. Note that only one groove-shaped opening aroundan interlayer insulating film in a sealing portion is provided in thisembodiment; however, a plurality of openings can be provided.Reliability is further improved by providing a plurality of openings.

Embodiment 2

In this embodiment, an embodiment regarding Embodiment Mode 5 andEmbodiment Mode 6 is described with reference to FIGS. 17 and 18A to18I. In FIG. 17, an interlayer insulating film has a single layerstructure; however, it may be regarded as having the same structure asin Embodiment 1. A structure of a first electrode in a light emittingelement is different, but it is described below.

FIG. 17 is a cross-sectional view taken along a line f-f′ in FIG. 3. InFIG. 17, an etching stopper film 250 is formed in a groove-shapedopening on the periphery of an interlayer insulating film and in aninterlayer insulating film removed portion on the periphery of asubstrate. The etching stopper film 250 can be formed at the same timeas formation of a semiconductor layer of a transistor in a drivercircuit portion or a pixel portion. It functions as an etching stopperin etching an interlayer insulating film 251 and has effect of improvingadhesiveness of a sealant made of an impermeable material by reducinggeneration of an etching residue or unevenness.

Since it is similar to Embodiment 1 up to manufacturing a sourceelectrode and a drain electrode except to have the etching stopper film250, explanation is omitted. After a source electrode and a drainelectrode are formed, a first electrode 252 of a light emitting elementis formed to be in contact with an electrode 255 of a switching TFT in apixel portion. In this embodiment, the first electrode 252 of the lightemitting element is manufactured over an interlayer insulating filmprovided with the source electrode and the drain electrode. Therefore,it is not necessary to manufacture a second interlayer insulating film.A material similar to the first electrode in Embodiment 1 can be used asa material for the first electrode 252 or the like, and a process aftermanufacturing the first electrode is similar to Embodiment 1; therefore,explanation is omitted.

Here, light can be extracted in a direction of a substrate 200 when thefirst electrode is made of a transparent conductive film typified byITO. In addition, light can be extracted in both directions of thesubstrate 200 and an opposing substrate 248 when a second electrode isalso similarly made of a transparent material.

FIGS. 18A to 18I show a method for manufacturing a region “c” in FIG. 3.FIGS. 18A to 18E are cross-sectional views taken along a line a-a′ inFIG. 3, and FIGS. 18F to 18I are top views of the region “c” in FIG. 3.FIGS. 18A to 18E and FIGS. 18F to 18I adjacent to each otherrespectively show a diagram of the same step. In FIGS. 18A to 181, aleft side is a direction of an FPC and a right side is a direction of adisplay portion. Since FIGS. 18F to 18I have a direction different fromthat in the region “c” in FIG. 3, it is necessary to be paid attentionto.

When a transistor and a first insulating film are formed in a displayportion in this embodiment, a base insulating film 301 is formed over asubstrate 300 in a wiring portion connecting an external terminal and aninternal circuit. An etching stopper film 302 (silicon film) is formedin a portion from which an interlayer film is removed over the baseinsulating film 301; an insulating film 303 functioning as a gateinsulating film is formed to cover the etching stopper film 302 (siliconfilm) and the base insulating film 301; and then, a first interlayerinsulating film 304 is formed to cover the same. An acrylic film or asiloxane film can be employed for the first interlayer film; however, asiloxane film is used in this embodiment (FIGS. 18A and 18F).

Thereafter, the first interlayer insulating film 304 is etched andremoved to have a tapered shape on an end face thereof, thereby formingan interlayer insulating film removed portion 305 on the periphery ofthe substrate. The etching stopper film 302 (silicon film) serving as anetching stopper is formed in advance in the interlayer insulating filmremoved portion 305. Therefore, a surface of the interlayer insulatingfilm removed portion 305 after removal is even, and unevenness due to anetching residue or gouge of a base film is not caused. (FIGS. 18B and18G)

Subsequently, a metal film 306 serving as a wiring is formed. The metalfilm may be made of the same material as the source electrode and thedrain electrode in the driver circuit portion or the pixel portion. Aspecific material is similar to the material for the source electrodeand the drain electrode in Embodiment 1 (FIGS. 18C and 18H).

The metal film 306 is etched simultaneously with etching for forming thesource electrode and the drain electrode in order to form a wiring 307.At this time, a portion without being covered with the wiring 307 of theetching stopper film 302 (silicon film) formed in the interlayerinsulating film removed portion 305 is removed by the etching. When anetching stopper film 302 which is not located below the wiring 307 andis formed in a position 308 below a remaining interlayer insulating film304 is previously formed in such a shape that it is separated from theetching stopper film 309 (silicon film) located below the wiring 307after wiring etching, wirings adjacent to each other do notshort-circuit, even if the etching stopper film 302 is made of aconductive material (FIGS. 18D, 18E, and 18I).

Generation of unevenness in the interlayer insulating film removedportion 305 can be prevented and generation of large unevenness on awiring to be formed thereafter can also be suppressed by forming theetching stopper film 302 (silicon film) as an etching stopper.Adhesiveness of a sealant made of an impermeable material to be formedthereover can be maintained, and water entering from a portion havingpoor adhesiveness of a sealant can be reduced.

When such a structure is employed, an interlayer insulating film can beremoved also in a wiring portion connecting an external terminal portion(such as an FPC) and an internal circuit, and the interlayer insulatingfilm can be prevented from being exposed to outer air. Consequently,water entry can drastically be reduced, which contributes to improvementin reliability of an electroluminescent device.

After removing the first interlayer insulating film on the periphery ofthe substrate to have a tapered shape on its end face and before formingmetal for a wiring, it is useful to form a nitride film such as asilicon nitride film or a carbon nitride film thereover by CVD in orderto prevent moisture from entering from an end face (not shown). Higherreliability can be obtained by forming such a nitride film.

In this embodiment, the first interlayer insulating film on theperiphery of the substrate is removed by the same step as opening of acontact hole in a pixel portion and a driver circuit portion. Therefore,in the pixel portion and a driver circuit portion, conduction between awiring in a lower layer or the like and a wiring formed over the firstinterlayer insulating film, which is to be performed through the contacthole, may not be made, when the nitride film is formed after removingthe first interlayer insulating film. Thus, in a portion which isrequired to electrically be in contact with a lower portion, a nitridefilm in the portion is preferably removed before forming metal for awiring. When a nitride film is formed over the first interlayerinsulating film, moisture can be prevented from entering from an endface of an interlayer insulating film in such a contact hole portion.Consequently, further higher reliability can be obtained.

Embodiment 3

In this embodiment, an example of a pixel structure in anelectroluminescent device to which a structure of the present inventionis applied is described with reference to FIGS. 19A and 19B.

FIGS. 19A and 19B show an element structure of one pixel. The displayportion in FIG. 3 is formed by arranging a plurality of such pixels inmatrix. Naturally, this pixel structure is merely an example, and anyother conceivable pixel structures may be employed.

In FIGS. 19A and 19B, a top emission structure is adopted. One pixelincludes a source line 400, a driver TFT gate line 401, an anode line402, an erasing gate line 403, a writing gate line 404, an erasing TFT405, a writing TFT 406, a driver TFT 407, a display TFT 408, an ACdriving diode 409, a capacitor 410, a drain electrode 411 of a driverTFT, and a driver TFT gate line 412.

Then, a light emitting element 413 is formed in an upper portion thereofthrough an insulating film, and an anode or a cathode of a lightemitting element is connected to the drain electrode 411 of a driverTFT.

Embodiment 4

In this embodiment, a structure of a source driver that is required todisplay an image in an electroluminescent device is described withreference to FIG. 20.

In a row where a gate signal line is selected, a shift register 500 (SR)outputs a sampling pulse sequentially from a first stage in accordancewith a clock pulse 504 and a start pulse 505. A first latch circuit 501takes in a video signal in timing with a sampling pulse being inputted,and the video signal taken in at each stage is stored in the first latchcircuit 501.

According to a sampling pulse outputted from one shift register 500,three latch circuits A, B, and C in the first latch circuit 501 take insignals inputted from video lines DATA 01 to 20, DATA 21 to 40, DATA 41to 60, respectively. A sampling pulse outputted from the shift register500 in the first stage takes in a video signal for being charged anddischarged in a source signal line from S01 to S60 among source signallines from S01 to S1920. In the first latch circuit that takes in avideo signal in response to a sampling pulse of the shift register 500in the first stage, the latch circuit A stores a video signal for sourcesignal lines from S01 to S20; B, from S21 to S40; and C, from S41 toS60. Subsequently, the first latch circuit that takes in a video signalin response to a sampling pulse outputted from the shift register in thesecond stage takes in a video signal for source signal lines from S61 toS120. The latch circuits A, B, and C store a video signal for sourcesignal lines from S61 to S80, from S81 to S100, and from S101 to S120,respectively. Similarly, a shift register in the 32nd stage takes in andstores a video signal for source signal lines from S1861 to S1920; then,taking in a video signal for one row is completed.

When a latch pulse (LAT) 506 is outputted after taking in a video signalfor one row is completed, the video signal stored in the first latchcircuit 501 is transferred to a second latch circuit 502 all at once,and all signal lines are charged and discharged all at once. A levelshifter and a buffer for making output from the second latch circuit 502a desired size may appropriately be provided as necessary.

The above-mentioned operation is repeated from the first row to the lastrow, thereby completing writing for one frame. Thereafter, similaroperations are repeated to display an image.

Note that a source driver having this structure is merely an example,and the present invention can be applied even if any other structures ofa source driver are employed.

Embodiment 5

A method for forming an end face of an insulating film into a taperedshape as described in Embodiment Mode 5 is described in this embodiment.

When isotropic etching such as wet etching can be performed and thereare a margin in etching and a certain film thickness, a tapered shapecan easily be obtained.

A method for forming an insulating film into a tapered shape byanisotropic dry etching is described in this embodiment.

First, a method for processing an object into a desired shape by dryetching using an etching mask previously manufactured by a conventionalmethod is described with reference to FIGS. 21A to 21E.

A mask material 602 such as a photosensitive resist or polyimide isformed over an entire surface of an object to be processed 601 byapplication or the like (FIG. 21A). A positive resist is given as anexample in this description.

Subsequently, pre-bake at low temperature for vaporizing and stabilizinga material in the resist is performed; thereafter, the resist ispartially exposed to light through a photomask 603 in a desired shape(FIG. 21B).

After a portion exposed to light by the light-exposure is dissolved indeveloper and is removed (FIG. 21C), baking is performed to improveadhesiveness of the resist and to improve resistance to an etchant to beused in the next step. An etching mask for an object is formed so far.The step so far is referred to as photolithography.

An object can be processed into a desired shape by etching the objectusing the mask and an appropriate etchant (FIG. 21D).

Here, the end face of the etching mask is at large angle to the objectlocated in a lower portion. Therefore, the end face of the object whichis located in a lower portion becomes steep reflecting the shape of theend face of the etching mask, when anisotropic etching such as dryetching is performed. When an interlayer insulating film on theperiphery of the substrate is removed and a wiring is formed in such away, an etching residue of a wiring as described in Embodiment Mode 4 or5 is generated on an end face of the interlayer insulating film, whichcauses a defect due to wiring short circuit.

Consequently, in forming a mask by photolithography, a slit 605 havingnarrower width than limit of resolution of a photolithography apparatusused for light-exposure is formed on an end face of a portion of thephotomask 604 which is preferably formed into a tapered shape. A maskmaterial such as a resist which is exposed to light through a slit and apattern having narrower width than resolution of a photolithographyapparatus is not completely exposed to light in the portion. A mask ofwhich film thickness is decreased remains even after removing alight-exposed portion with developer.

An incomplete light-exposed portion as described above is providedbetween a non-light-exposed portion and a complete light-exposed portionin a photosensitive mask material such as a resist by thus forming aslit or a hole having width equal to or narrower than light-exposureresolution of a photolithography apparatus in a photomask. Accordingly,an end face of an etching mask can be formed into a tapered shape.

When anisotropic etching typified by dry etching is performed using theetching mask having a tapered shape under such a condition that both theobject in a lower layer and the mask are etched, the etching maskdisappears where thickness thereof is thin at the same time that theobject is etched. According to disappearance of the etching mask, anobject newly exposed to etching atmosphere is sequentially etched,thereby obtaining an object having a shape nearly reflecting a shape ofthe etching mask (FIGS. 21F to 21J).

An object (an interlayer insulating film in Embodiment Mode 5) having asimilar tapered shape on an end face thereof is obtained by using theetching mask having a tapered shape on an end face thereof.

A shape of a photosensitive material after development can freely beformed depending on shapes of a slit, a pattern, and a hole of aphotomask in exposing to light. FIGS. 22A to 22D show an examplethereof. FIGS. 22A and 22C are SEM pictures of a sample in which asiloxane film is formed over a substrate, a resist is applied thereover,exposed to light with a photomask 700, and etched by dry etching, andFIGS. 22B and 22D are schematic diagrams of a photomask. The SEMpictures show that a resist is exposed to light with a photomask havingsuch a pattern as the photomask 700 shown in FIG. 22B or 22D.

While only a portion 701 is exposed to light with a typical photomask, across-sectional shape as shown in the SEM picture can be obtained inFIGS.22A to 22D by forming a pattern 702 equal to or narrower than limitof resolution of a photolithography apparatus in a photomask.

As shown in FIGS. 22A to 22D, an object can have various shapes bychanging a shape of the pattern 702 equal to or narrower than limit ofresolution of a photolithography apparatus. An object having a shapethat cannot be formed ever before can be manufactured by appropriatelychanging an object material and an etching condition using the thusformed etching mask.

Embodiment 6

Examples of electronic devices to which the present invention is appliedcan be given as a video camera, a digital camera, a goggle type display(head mounted display), a navigation system, an audio reproducing device(car audio, an audio component, or the like), a laptop personalcomputer, a game machine, a personal digital assistant (a mobilecomputer, a cellular phone, a portable game machine, an electronic book,or the like), and an image reproducing device including a recordingmedium (specifically, a device capable of processing data in a recordingmedium such as a Digital Versatile Disk (DVD) and having a display thatcan display the image of the data). Practical examples of theseelectronic devices are shown in FIGS. 23A to 23E.

FIG. 23A shows a wall-mounted display device, which includes a chassis2001, a display portion 2003, a speaker portion 2004, and the like. Thepresent invention is applied to manufacturing of the display portion2003. Longer-term reliability can be secured by employing the presentinvention.

FIG. 23B shows a digital still camera, which includes a main body 2101,a display portion 2102, an image receiving portion 2103, operation keys2104, an external connection port 2105, a shutter 2106, and the like.The present invention can be applied to the display portion 2102.Although a digital still camera is often used outside and tends to beput in a harder condition than indoors, long-term reliability can beobtained even under a comparatively hard condition by employing thepresent invention.

FIG. 23C shows a laptop personal computer, which includes a main body2201, a chassis 2202, a display portion 2203, a keyboard 2204, anexternal connection port 2205, a pointing mouse 2206, and the like. Thepresent invention can be applied to the display portion 2203. A laptoppersonal computer can conceivably be carried around and used, which isdifferent from a desktop computer. Similarly as a digital still camera,possibility of use under a more adverse condition than a monitor of adesktop computer increases by being carried around. Longer-termreliability can be secured even under such a condition by employing thepresent invention.

FIG. 23D shows a mobile computer, which includes a main body 2301, adisplay portion 2302, a switch 2303, operation keys 2304, an infraredport 2305, and the like. The present invention can be applied to thedisplay portion 2302. Although a mobile computer is often used outsideand tends to be put in a harder condition than indoors, long-termreliability can be obtained even under a comparatively hard condition byemploying the present invention.

FIG. 23E shows a portable game machine, which includes a chassis 2401, adisplay portion 2402, a speaker portion 2403, operation keys 2404, arecording medium insertion portion 2405, and the like. The presentinvention can be applied to the display portion 2402. Although aportable game machine is often used outside and tends to be put in aharder condition than indoors, long-term reliability can be obtainedeven under a comparatively hard condition by employing the presentinvention.

As described above, the applicable range of the present invention is sowide that the invention can be applied to electronic devices of variousfields. In addition, reliability of a product improves, so thatreliability as a manufacturer can also be improved.

This application is based on Japanese Patent Application serial no.2003-347601 filed in Japan Patent Office on Aug. 29 in 2003 and no.2003-322334 filed on Sep. 12 in 2003, the contents of which are herebyincorporated by reference.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless otherwise such changes andmodifications depart from the scope of the present invention hereinafterdefined, they should be construed as being included therein.

1. A light emitting device comprising: a first substrate; a thin filmtransistor over the first substrate; a first interlayer insulating filmformed over the thin film transistor; a source or drain electrode formedon the first interlayer insulating film; a light emitting element formedover the first interlayer insulating film; a second interlayerinsulating film formed over the first interlayer insulating film; and asecond substrate provided over the light emitting element, wherein aside surface of the first interlayer insulating film is tapered at aregion in which the first and second substrates are fixed to each otherwith a sealing material, wherein the side surface of the firstinterlayer insulating film is covered and in contact with a firstprotective film, wherein a side surface of the first protective film iscovered with the second interlayer insulating film, wherein a sidesurface of the second interlayer insulating film is covered and incontact with a second protective film, wherein the sealing materialcovers the side surface of the first interlayer insulating film and theside surface of the second interlayer insulating film at the region, andwherein the first protective film is the same material as the source ordrain electrode.
 2. A light emitting device according to claim 1,wherein the light emitting element is electrically connected to a thinfilm transistor.
 3. A light emitting device according to claim 1,wherein at least one of the first and the second interlayer insulatingfilms comprises an organic material.
 4. A light emitting deviceaccording to claims 1, wherein at least one of the first and the secondinterlayer insulating films comprises an inorganic material.
 5. A lightemitting device according to claim 1, wherein at least one of the firstand the second interlayer insulating films comprises a film includingsiloxane moiety.
 6. A light emitting device according to claim 3,wherein the organic material is acrylic.
 7. A light emitting deviceaccording to claim 3, wherein the organic material is polyimide.
 8. Alight emitting device according to claim 1, wherein the light emittingdevice is incorporated into an electronic device selected from the groupconsisting of a display device, a camera, a computer, a portableinfoimation terminal, and a game apparatus.
 9. A light emitting deviceaccording to claim 1, wherein said side surface of said secondinterlayer insulating film covers said side surface of said firstinsulating film.
 10. A light emitting device according to claim 1,wherein said second protective film covers said first protective film.11. A light emitting device comprising: a first substrate; a firstinterlayer insulating film formed over the first substrate; a source ordrain electrode formed on the first interlayer insulating film; a lightemitting element formed over the first interlayer insulating film; asecond interlayer insulating film formed over the first interlayerinsulating film; and a second substrate provided over the light emittingelement, wherein a first opening is Ruined in the first interlayerinsulating film at a region in which the first and second substrates arefixed to each other with a sealing material, wherein the first openingis covered with a first protective film, wherein a side surface of thefirst protective film is covered with the second interlayer insulatingfilm, wherein a second opening is formed in the second interlayerinsulating film at the region, wherein the second opening is coveredwith a second protective film, wherein the second protective film is incontact with the second interlayer insulating film and is formed overthe first protective film, wherein a side surface of the firstinterlayer insulating film is tapered at the region, wherein the sealingmaterial covers the side surface of the first interlayer insulating filmand a side surface of the second interlayer insulating film at theregion, and wherein the first protective film is the same material asthe source or drain electrode.
 12. A light emitting device according tothe claim 11, wherein at least one of the first and the secondprotective films is impermeable.
 13. A light emitting device accordingto claim 11, wherein the light emitting element is electricallyconnected to a thin film transistor.
 14. A light emitting deviceaccording to claim 11, wherein at least one of the first and the secondinterlayer insulating films comprises an organic material.
 15. A lightemitting device according to claim 11, wherein at least one of the firstand the second interlayer insulating films comprises an inorganicmaterial.
 16. A light emitting device according to claim 11, wherein atleast one of the first and the second interlayer insulating filmscomprises a film including siloxane moiety.
 17. A light emitting deviceaccording to claim 14 , wherein the organic material is acrylic.
 18. Alight emitting device according to claim 14, wherein the organicmaterial is polyimide.
 19. A light emitting device according to claim11, wherein the light emitting device is incorporated into an electronicdevice selected from the group consisting of a display device, a camera,a computer, a portable information terminal, and a game apparatus.
 20. Alight emitting device according to claim 11, wherein said side surfaceof said second interlayer insulating film covers said side surface ofsaid first interlayer insulating film.
 21. A light emitting deviceaccording to claim 11, wherein said second protective film covers saidfirst protective film.